Continuously-variable transmissions are useful for reducing the energy consumption and/or simplifying the control of land vehicles and some machinery. However, mechanical transmissions of this type generally require friction wheels, chains, or belts which are less efficient, durable, and compact than conventional geared transmissions. These include, for example, U.S. Pat. No. 1,165,410 to Hitchcock, U.S. Pat. No. 2,545,152 to Haidegger, U.S. Pat. No. 3,802,295 and U.S. Pat. No. 3,850,050 to Lemmons, U.S. Pat. No. 4,386,536 to Kraus and the transmissions described and referred to in the article, "The CVT Gearless Transmission" by P. Weissler in Mechanics Illustrated, March, 1983, p.p. 68-76 and 122. Continuously-variable electrical, hydraulic, or pneumatic transmissions also encounter losses because of the conversions from mechanical to the other forms of energy and back again.
Energy consumption can be reduced by using flywheels to store and release energy. Flywheel energy storage can allow an engine to operate intermittently at favorable loads and allow recovery of energy that would otherwise be dissipated by braking. Continuously-variable transmissions have been necessary to match the speed of such flywheels with the required output speed.
Many torque transmission devices are controlled by or employ movable flyweights. These include the following U.S. Pat. Nos. 1,759,466 to Porter, 1,831,633 to Morici, 1,867,590 to Porter, 1,878,727 to Sturbelle, 2,196,654 to Betran.
The inertia generated by the flyweights is controlled strictly by the speed of a rotating shaft and is thus predetermined for any speed of the shaft. Any energy storage in the flyweights is incidental and cannot be used as a controllably variable source of rotational energy or momentum.
U.S. Pat. No. 3,851,545 to Gamlich describes a continuously variable transmission employing pairs of gyros. Power transmission is entirely through gearing. Although the gyros store considerable energy, that energy is neither obtained from the output shaft nor transmittable to the output shaft. Thus, there is no useful energy storage provided between the prime mover and the load.